1. Field of the Invention
The present invention substantially relates to a method of segmenting a wafer, and more particularly, to a method that allows automatic wafer expansion and wafer sorting after dicing the wafer.
2. Description of the Prior Art
In the fabrication of semiconductor chips or MEMS chips, a wafer is first treated with tens or more than hundreds of processes to form a plurality of semiconductor devices or MEMS devices. The wafer is subsequently diced by a dicing process to form a plurality of dies. The dies are thereafter packaged so as to form a plurality of chips able to be electrically connected to printed circuit boards.
Please refer to FIG. 1, which is a schematic diagram illustrating a conventional method of performing a dicing process with a dicing apparatus. As shown in FIG. 1, a wafer 10 to undergo a dicing process is bonded to a bonding layer 12, such as a tape. The bonding layer 12 meanwhile is bonded to a supporting frame 14 so as to fasten the position of the wafer 10. When the wafer 10 is accurately aligned in the dicing apparatus, a cutter 16 is exploited through predetermined scribe lines to segment the wafer 10 into a plurality of dies 18. Selectively, a wafer expansion process can be performed according to the dimension of the scribe lines by expanding the bonding layer 12, so as to enlarge the gap between two adjacent dies 18 for the convenience of a further wafer sorting process.
The above method is the most common way to dice the wafer 10. However, since the width of the cutter 16 is no longer ignorable as the critical dimension of semiconductor processes decreases and the improvement of wafer integration, the dicing process using the cutter 16 is no longer able to dice a wafer with high integration. Therefore, a dicing process by way of etching is another choice.
Please refer to FIG. 2, which is a conventional method of performing a dicing process in an etching manner. As shown in FIG. 2, a wafer 30, having a photoresist pattern 36 disposed thereon for defining scribe lines, is bonded to a carrier 34 with a bonding layer 32. Then, an anisotropic etching process is performed to etch the wafer 30 uncovered by the photoresist pattern 36 until the wafer 30 is etched through so as to form a plurality of dies 38.
The above method is able to reduce the dimension of the scribe lines so as to increase the amounts of dies 30 arranged in the wafer. However, due to the narrowness of the scribe lines, the wafer sorting process cannot be easily performed after the dicing process. In addition, since the carrier 34, such as a bare wafer, is a rigid structure, the wafer expansion process in which the bonding layer 32 is extended to increase the gap of the dies 38 cannot be carried out. In such a case, the photoresist pattern 36 is removed in advance, and then the bonding layer 32 is removed to separate the dies 38 from the carrier 34. Following that, the dies 38 are picked up and sorted manually. Accordingly, the throughput is reduced and the dies 38 may be damaged.